Figure out exactly what those wheels are and market them as such. Those wheels were not factory options on any 450SEL. They look to me to be off an early 190E. To be sure, get the numbers off the back of the wheel. Look for a string like 6J14H2 ET30 or 6,5J15H2 ET21,5 or something like that. The prefix of the part number will tell/guide you as to which MB series they're from. The part number is something like 201 400 0101 or 124 400 0101 or something like that.
$200 sounds about right. Check eBay for comparable items. Tires are a gotcha because they make the set that much more difficult and expensive to ship.